Electrode assembly, single battery and electrode assembly processing method

Abstract

The invention discloses an electrode assembly, a single battery and an electrode assembly processing method.The electrode assembly comprises a positive plate and a negative plate which are alternately stacked and a diaphragm clamped between the positive plate and the negative plate, the positive plate comprises a positive current collector and a positive coating, the positive coating is arranged on the surface of one side of the positive current collector at intervals, and the negative coating is arranged on the surface of the other side of the positive current collector; positive grooves are formed in the two ends of each section of the positive electrode coating; the negative plate comprises a negative current collector and a negative coating arranged on the surface of one side of the negative current collector, and a negative groove is formed in the area, opposite to the positive groove, of the negative coating. The positive electrode groove directly reduces the potential upper limit of lithium deintercalation and intercalation in the area, and excessive supply of local positive electrodes to negative electrodes is avoided; and the consumption rate of the area to lithium ions is improved through the change of the structure morphology of the negative electrode groove, so that the negative electrode can absorb the entering lithium ions more easily in a diffusion and embedding manner under the condition of high rate or rapid charging, and metal lithium cannot be rapidly accumulated on the surface.

Description

Technical Field

[0001] This application relates to the field of energy storage equipment technology, and in particular to an electrode assembly, a single cell, and a method for processing the electrode assembly. Background Technology

[0002] Lithium-ion batteries typically consist of a positive electrode, a negative electrode, and a separator wound or stacked together. The positive and negative electrodes each include a current collector and an active material coating. During charging and discharging, lithium ions migrate back and forth between the positive and negative electrodes under the influence of the electrolyte, inserting into / extracting from the corresponding active material lattice, thus realizing the interconversion of electrical energy and chemical energy.

[0003] Under high-rate charge / discharge or fast-charging conditions, metallic lithium is prone to deposit on the negative electrode surface. Some lithium ions cannot be stored in the intercalation form and instead deposit as metal on the negative electrode surface, forming the so-called "lithium plating" phenomenon. Lithium plating is more common at the beginning and end of the active material coating application, where the coating thickness is difficult to control precisely and is close to the electrode tab.

[0004] Therefore, reducing lithium plating while ensuring battery energy density and energy storage performance is of great significance for optimizing battery safety and improving charge and discharge efficiency. Summary of the Invention

[0005] One objective of this application is to provide an electrode assembly, a single cell, and a method for processing the electrode assembly, which aims to solve the technical problem in the related art that high-rate charging and discharging easily leads to lithium plating on the negative electrode.

[0006] To achieve the above objectives, in a first aspect, this application provides an electrode assembly, including alternately stacked positive and negative electrode sheets, and a separator sandwiched between the positive and negative electrode sheets: the positive electrode sheet includes a positive current collector and a positive electrode coating, the positive electrode coating being spaced apart on the surface of the positive current collector, and positive grooves being formed at both ends of each segment of the positive electrode coating; the negative electrode sheet includes a negative current collector and a negative electrode coating being disposed on the surface of the negative current collector, and negative grooves being formed in the area of ​​the negative electrode coating opposite to the positive grooves.

[0007] In this application, positive grooves are formed at both ends of each positive electrode coating segment. This reduces the volume of the positive electrode active material in the edge region of the coating, limiting the amount of lithium available for insertion / extraction during charging. This reduces the potential local lithium flux and concentration peaks in this region, minimizing the impact on the corresponding negative electrode region. Simultaneously, a negative groove is formed in the region opposite the positive groove on the negative electrode sheet. This allows the negative electrode coating to form a more complex geometric interface and a larger actual surface area within the same projected area, increasing the contact interface and reaction area for lithium ions in this local region. This enables faster lithium insertion and consumption during electrode assembly operation. Therefore, this application reduces the amount of lithium ions generated at the positive electrode while increasing the rate of lithium ion consumption at the negative electrode, effectively reducing the risk of lithium plating on the negative electrode side of the electrode assembly.

[0008] On the one hand, the positive electrode groove directly reduces the potential upper limit of lithium insertion / extraction in this region, avoiding excessive supply of lithium ions from the local positive electrode to the negative electrode. On the other hand, the negative electrode groove, through changes in structural morphology, increases the rate of lithium ion consumption in this region, making it easier for the negative electrode to absorb incoming lithium ions through diffusion and insertion under high-rate or fast-charging conditions, rather than rapidly accumulating them into metallic lithium on the surface. Compared with related technologies, this application achieves simultaneous control of both the positive and negative electrodes at the edge of the positive electrode coating, which is more conducive to homogenizing current distribution, reducing local polarization, and suppressing the risk of lithium plating.

[0009] In conjunction with the first aspect, according to one embodiment of this application, in the extension direction of the positive current collector, the depth of the positive groove decreases as it approaches the end of the positive electrode coating; and / or a plurality of positive grooves are formed on the same section of the positive electrode coating, adjacent positive grooves are interconnected in the extension direction of the positive current collector, and the positive grooves near the end of the positive electrode coating have a greater groove depth than the positive grooves away from the end.

[0010] In conjunction with the first aspect, according to one embodiment of this application, there are multiple negative grooves, and adjacent negative grooves are spaced apart.

[0011] In conjunction with the first aspect, according to one embodiment of this application, the groove wall of the negative groove is perpendicular to the surface of the negative current collector used for coating the negative electrode coating.

[0012] In conjunction with the first aspect, according to one embodiment of this application, the positive electrode coating includes a positive subtractive material region and a positive uniform coating region, the positive subtractive material region being used to form positive grooves, and the positive uniform coating region being uniformly coated with positive active material; the negative electrode coating includes a negative subtractive material region and a negative uniform coating region, the negative subtractive material region being used to form negative grooves, and the negative uniform coating region being uniformly coated with negative active material, the average thickness of the positive uniform coating region being the same as the average thickness of the negative uniform coating region, and the average thickness of the positive subtractive material region being less than the average thickness of the negative subtractive material region.

[0013] In conjunction with the first aspect, according to one embodiment of this application, the negative material reduction area is further provided with a compensating ridge, which is sandwiched between two adjacent negative grooves.

[0014] In conjunction with the first aspect, according to one embodiment of this application, the number of positive grooves corresponding to each positive electrode coating is positively correlated with the charge and discharge rate of the electrode assembly, and the number of negative grooves is positively correlated with the number of positive grooves.

[0015] In conjunction with the first aspect, according to one embodiment of this application, the positive current collector, the negative current collector, the positive electrode coating, the negative electrode coating, and the separator all extend in a first direction, the positive groove penetrates the positive electrode coating in a second direction, and the negative groove penetrates the negative electrode coating in a second direction; wherein, the second direction is parallel to the surfaces of the positive current collector and the negative current collector and is perpendicular to the first direction.

[0016] In conjunction with the first aspect, according to one embodiment of this application, each negative groove has a dimension of 8-12 mm in the first direction, and the average depth of each negative groove is 1 / 4-1 / 3 of the thickness of the negative electrode coating; and / or each positive groove has a dimension of 5-10 mm in the first direction, and the average depth of each positive groove is 1 / 4-1 / 3 of the thickness of the positive electrode coating.

[0017] In conjunction with the first aspect, according to one embodiment of this application, a positive electrode coating is disposed on one side surface or opposite two sides surface of the positive current collector; and / or, a negative electrode coating is disposed on one side surface or opposite two sides surface of the negative current collector.

[0018] Secondly, this application also provides a single-cell battery, including any of the above-mentioned electrode assembly and housing, wherein the electrode assembly is disposed within the housing.

[0019] Thirdly, this application also provides an electrode assembly processing method, comprising the following steps: providing a positive current collector, and applying a positive electrode coating at intervals on the surface of the positive current collector; providing a negative current collector, and applying a negative electrode coating on the surface of the negative current collector; forming positive grooves at both ends of each segment of the positive electrode coating, and forming negative grooves on the negative electrode coating; providing a separator, and stacking the positive current collector, the negative current collector, and the separator, such that the positive electrode coating and the negative electrode coating alternately sandwich the separator, with the positive grooves facing the negative grooves.

[0020] The beneficial effects of the second and third aspects mentioned above can be referred to in the first aspect or any possible implementation of the first aspect, and will not be elaborated here. Based on the implementations provided in the above aspects, this application can also be further combined to provide more implementations.

[0021] Other advantages, objectives and features of this application will be partly apparent from the description below, and partly understood by those skilled in the art through study and practice of this application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the electrode assembly provided in the embodiments of this application; Figure 2 yes Figure 1 A magnified view of a portion of region A in the middle; Figure 3 This is a schematic diagram of the overall structure of the positive and negative electrode plates provided in the embodiments of this application; Figure 4 This is a front view of the positive and negative electrode plates provided in the embodiments of this application; Figure 5 yes Figure 3 A magnified view of a portion of region B in the middle; Figure 6 This is one of the partial side views of the positive electrode sheet provided in the embodiments of this application; Figure 7 This is a second partial side view of the positive electrode sheet provided in the embodiments of this application; Figure 8 This is a third partial side view of the positive electrode sheet provided in the embodiments of this application; Figure 9 This is one of the partial side views of the negative electrode sheet provided in the embodiments of this application; Figure 10 This is a second partial side view of the negative electrode sheet provided in the embodiments of this application; Figure 11 This is a partial structural schematic diagram of the electrode assembly provided in an embodiment of this application.

[0024] Explanation of icon numbers: 10. Positive electrode sheet; 11. Positive current collector; 12. Positive electrode coating; 121. Positive groove; 122. Positive subtractive material region; 123. Positive uniform coating region; 13. Positive tab; 20. Negative electrode sheet; 21. Negative current collector; 22. Negative electrode coating; 221. Negative groove; 222. Negative subtractive material region; 223. Negative uniform coating region; 234. Compensating ridge; 23. Negative tab; 30. Separator. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] A lithium-ion battery typically consists of a positive electrode, a negative electrode, and a separator sandwiched between the two electrodes. The positive electrode includes a positive current collector and a coating of positive active material on the surface of the current collector. The negative electrode includes a negative current collector and a coating of negative active material on the surface of the current collector. During charging and discharging, lithium ions migrate back and forth between the positive and negative electrodes under the action of the electrolyte, inserting into or extracting from the corresponding active material lattice to achieve the interconversion of electrical energy and chemical energy.

[0027] Under high-rate charge / discharge or fast-charging conditions, the surface potential of the negative electrode decreases rapidly. If the local current density is too high or the local negative electrode capacity is insufficient, lithium metal deposition can easily occur on the negative electrode surface. Specifically, during charging, when the lithium intercalation capacity of the negative electrode is rapidly depleted and recovers slowly, and when local polarization is severe and the concentration gradient is too large, some lithium ions cannot be stored in the intercalated form but are deposited on the negative electrode surface in a metallic state, forming a "lithium deposition" phenomenon. Lithium deposition not only causes reversible capacity loss but may also gradually grow into dendrites after multiple cycles, piercing the separator and inducing internal short circuits, thus posing a serious safety risk.

[0028] In the actual design of electrode assemblies, active materials often need to be coated at intervals along the length of the electrode sheet (hereinafter referred to as skip coating) to arrange tabs or achieve inter-sheet connections in uncoated areas. Due to limitations in the processing technology, fluctuations in the start and stop positions of the coating process are unavoidable. The start and end points of the skip coating section usually exhibit non-uniformity in thickness, density, and microstructure, making these edge areas more prone to localized high current density and uneven lithium-ion concentration distribution during charging and discharging. When electrode assemblies are stacked, the edge area of ​​the positive electrode coating may form a locally higher lithium concentration and stronger polarization during charging, thereby applying a higher lithium-ion intercalation pressure to the opposite negative electrode coating area. If the negative electrode in this area cannot intercalate lithium in a timely and uniform manner, metallic lithium is prone to precipitation at the opposite position of the negative electrode sheet, increasing the risk of dendrite growth and safety hazards.

[0029] Please see Figures 1 to 6 As shown, Figure 1 This is a schematic diagram of the overall structure of the electrode assembly provided in the embodiments of this application; Figure 2 yes Figure 1 A magnified view of a portion of region A in the middle; Figure 3 This is a schematic diagram of the overall structure of the positive electrode 10 and the negative electrode 20 provided in the embodiments of this application; Figure 4 This is a front view of the positive electrode 10 and the negative electrode 20 provided in the embodiments of this application; Figure 5 yes Figure 3 A magnified view of a portion of region B in the middle; Figure 6 This is one of the partial side views of the positive electrode 10 provided in the embodiments of this application.

[0030] To address the aforementioned technical problems, this application discloses an electrode assembly comprising alternately stacked positive electrode plates 10 and negative electrode plates 20, and a separator 30 sandwiched between the positive and negative electrode plates: The positive electrode 10 includes a positive current collector 11 and a positive electrode coating 12. The positive electrode coating 12 is disposed at intervals on the surface of the positive current collector 11, and positive grooves 121 are formed at both ends of each segment of the positive electrode coating 12. The negative electrode 20 includes a negative current collector 21 and a negative electrode coating 22 disposed on the surface of the negative current collector 21. The negative electrode coating 22 has a negative groove 221 in the area opposite to the positive groove 121.

[0031] In this application, positive grooves 121 are formed at both ends of each positive electrode coating 12, which reduces the volume of the positive electrode active material in the edge region of the coating. This limits the amount of lithium available for insertion and extraction during charging, reducing the potential local lithium flux and concentration peaks in this region from the generation end, thus reducing the impact on the corresponding negative electrode region. In other words, the ratio of negative electrode capacity to positive electrode capacity (i.e., NP ratio) of the electrode assembly is adjusted by the positive grooves 121. Simultaneously, a negative groove 221 is formed in the region of the negative electrode sheet 20 opposite to the positive grooves 121, allowing the negative electrode coating 22 to form a more complex geometric interface and a larger actual surface area within the same projected area of ​​this region. This increases the contact interface and reaction area for lithium ions in this local region, enabling faster lithium insertion and consumption during electrode assembly operation. Therefore, this application reduces the amount of lithium ions generated at the positive electrode while increasing the rate of lithium ion consumption at the negative electrode, effectively reducing the risk of lithium plating on the negative electrode side of the electrode assembly.

[0032] On the one hand, the positive electrode groove directly reduces the potential upper limit of lithium insertion / extraction in this region, avoiding excessive supply of lithium ions from the local positive electrode to the negative electrode. On the other hand, the negative electrode groove, through changes in structural morphology, increases the rate of lithium ion consumption in this region, making it easier for the negative electrode to absorb incoming lithium ions through diffusion and insertion under high-rate or fast-charging conditions, rather than rapidly accumulating them into metallic lithium on the surface. Compared with related technologies, this application achieves simultaneous control of both the positive and negative electrodes at the edge of the positive electrode coating, which is more conducive to homogenizing current distribution, reducing local polarization, and suppressing the risk of lithium plating.

[0033] It should be understood that forming a negative groove 221 on the negative electrode coating 22 will obviously reduce the mass of the negative electrode active material in that region in terms of thickness or local volume, objectively reducing the total amount of lithium that can be embedded in that region under extreme conditions, i.e., the upper limit of saturated lithium-ion throughput in the corresponding region is reduced. However, the solution in this application does not create grooves on the negative electrode side alone, but simultaneously forms positive grooves 121 in the corresponding positive electrode side region, which reduces the total amount of lithium available for insertion and extraction in that region. Therefore, in actual operation, it is difficult for this region to be pushed to the upper limit of saturated throughput of the negative electrode. In other words, although the corresponding region of the negative electrode has decreased in terms of static capacity, the corresponding positive electrode is also reduced in material, limiting the amount of lithium source, making it difficult for the negative electrode to become saturated even with some material reduction. On this basis, the effect brought by the negative groove 221 is more prominently manifested in the increased consumption rate of lithium ions absorbed and diffused in this region due to the increased surface area and changes in interface morphology.

[0034] It should be noted that the improvements in this application only involve morphological improvements on the positive electrode coating 12 and the negative electrode coating 22. Therefore, those skilled in the art can select different positive current collectors 11, negative current collectors 21 and separators 30 according to actual needs, and coat various optional active materials as positive electrode coatings 12 and negative electrode coatings 22. This application does not limit the selection of materials, the width of positive electrode sheet 10 / negative electrode sheet 20 / separator 30, the position of positive electrode tab 13 / negative electrode tab 23, the spacing of skip coating, etc., and should not limit the scope of protection of this application based on these limitations.

[0035] Furthermore, since the improvements in this application only involve the structure of the positive electrode 10 and the negative electrode 20, as well as the correspondence between the positive groove 121 and the negative groove 221, the electrode assembly of this application can be either a core or a stack core, and its application scenarios can be imagined as various forms of energy storage devices such as cylindrical batteries and square batteries.

[0036] For example, the width of a single negative groove 221 is 90-100 μm, the depth of the negative groove 221 is 1 / 3-1 / 4 of the thickness of the negative electrode coating 22, and the spacing between adjacent negative grooves 221 is 1.2-1.4 mm; the width of a single positive groove 121 is 90-100 μm, the depth of the positive groove 121 is 1 / 3-1 / 4 of the thickness of the positive electrode coating 12, and the spacing between adjacent positive grooves 121 is 1.2-1.4 mm. The widths here should be understood as the dimensions of the positive groove 121 and the negative groove 221 in the extending directions of the positive electrode sheet 10 and the negative electrode sheet 20, i.e., the dimensions in the first direction shown in the figures.

[0037] Please refer to Figure 7 and Figure 8 As shown, Figure 7 This is a second partial side view of the positive electrode 10 provided in the embodiments of this application; Figure 8This is a third partial side view of the positive electrode sheet 10 provided in the embodiments of this application. According to one embodiment of this application, in the extending direction of the positive current collector 11, the depth of the positive groove 121 decreases as it approaches the end of the positive electrode coating 12; and / or, a plurality of positive grooves 121 are formed on the same section of the positive electrode coating 12, adjacent positive grooves 121 are interconnected in the extending direction of the positive current collector 11, and the positive groove 121 near the end of the positive electrode coating 12 has a greater groove depth than the positive groove 121 away from the end.

[0038] This embodiment provides two specific configurations of the positive groove 121. Both exhibit a trend where the positive groove 121 becomes deeper and the average thickness of the positive electrode coating 12 decreases as the coating area increases. The position closest to the coating end experiences the most reduction in active material, resulting in a greater suppression of lithium-ion generation. As the distance from the end increases, the reduction gradually decreases, and the local capacity gradually recovers. Thus, the reduction in the upper limit of lithium-ion throughput brought about by the positive groove 121 is transitioned relatively smoothly, avoiding sharp overload points at certain narrow locations. This makes the lithium-ion impact on the corresponding negative electrode area more moderate, thereby further reducing the risk of local lithium plating and polarization concentration at the end.

[0039] Please refer to Figure 9 As shown, Figure 9 This is one of the partial side views of the negative electrode 20 provided in the embodiments of this application. According to one embodiment of this application, there are multiple negative grooves 221, and adjacent negative grooves 221 are spaced apart.

[0040] In this embodiment, the negative grooves 221 are spaced apart from each other instead of being connected to form a whole groove. On the one hand, a multi-peak and multi-valley undulating structure is formed on the surface of the negative electrode 20, which significantly increases the actual surface area of ​​the negative electrode 20 per unit length, which is beneficial to the expansion of the reaction interface and the dispersion of local current density.

[0041] According to one embodiment of this application, the groove wall of the negative groove 221 is perpendicular to the surface of the negative current collector 21 on which the negative electrode coating 22 is applied.

[0042] The vertical groove walls further increase the surface area of ​​the negative electrode coating 22. Each spaced negative groove 221 forms more boundaries on the sidewalls and bottom, increasing the number of effective interfaces that the electrolyte can contact and wet. The geometry is more complex and more conducive to the consumption of lithium ions.

[0043] It should be understood that the structures of the positive groove 121 and the negative groove 221 in this application are not related, and they independently play the roles of suppressing lithium ion generation and accelerating lithium ion consumption. In a preferred embodiment, the positive electrode 10 uses interconnected positive grooves 121 to reduce the surface area, and the negative electrode 20 uses spaced negative grooves 221 to increase the surface area.

[0044] According to one embodiment of this application, the positive electrode coating 12 includes a positive subtractive material region 122 and a positive uniform coating region 123. The positive subtractive material region 122 is used to form a positive groove 121, and the positive uniform coating region 123 is uniformly coated with positive electrode active material. The negative electrode coating 22 includes a negative subtractive material region 222 and a negative uniform coating region 223. The negative subtractive material region 222 is used to form a negative groove 221, and the negative uniform coating region 223 is used to uniformly coat the negative electrode active material. The average thickness of the positive uniform coating region 123 is the same as the average thickness of the negative uniform coating region 223, and the average thickness of the positive subtractive material region 122 is less than the average thickness of the negative subtractive material region 222.

[0045] In this embodiment, the average thickness of the positive subtractive material region 122 is less than the average thickness of the negative subtractive material region 222, further increasing the upper limit difference in lithium-ion throughput between the positive electrode 10 and the negative electrode 20 in the positive electrode skip coating area. This ensures that the negative electrode 20 side can stably consume the lithium ions released from the positive electrode 10 side, avoiding lithium plating. Since the average thickness of the positive uniform coating region 123 is the same as the average thickness of the negative uniform coating region 223, the adjustment is limited to the vicinity of the positive electrode skip coating area, without affecting other sections. This improves the compatibility of the electrode assembly of this application, enabling it to adapt to existing battery structures without significant structural adjustments.

[0046] For example, the length of the negative subtraction region 222 is 8-12mm, and the length of the positive subtraction region 122 is 5-10mm.

[0047] Please refer to Figure 10 , Figure 10 This is a second partial side view of the negative electrode 20 provided in an embodiment of this application. According to one embodiment of this application, the negative subtraction region 222 is further provided with a compensating ridge 234, which is sandwiched between two adjacent negative grooves 221.

[0048] Similar to the above embodiment in setting the positive subtractive material region 122 and the negative subtractive material region 222, this embodiment sets a compensation ridge 234 between the negative subtractive material grooves of the phase to increase the actual volume of the negative electrode coating 22 in the corresponding area, ensuring that the negative electrode sheet 20 side can stably consume the lithium ions released by the positive electrode sheet 10 side and avoid the occurrence of lithium plating.

[0049] For example, the compensation ridge 234 can be obtained by processing in the following manner: Pressure is applied to the surface of the negative electrode coating 22, forming a negative groove 221 while simultaneously pushing the active material within the negative groove 221 outwards, forming a compensating ridge 234. The applied pressure here can be either precisely controlled physical pressure, or it can be ion bombardment or wind pressure. Those skilled in the art can set it according to actual conditions. Here, only one volume transfer scheme is given to distinguish it from the scheme commonly used in the art, which results in direct volume loss due to laser ablation.

[0050] It should be understood that in existing electrode structures, the active material can be coated on one or both sides of the current collector, and this application is no exception. Specifically, the positive electrode coating 12 is disposed on one side or opposite sides of the positive current collector 11; the negative electrode coating 22 is disposed on one side or opposite sides of the negative current collector 21. For clarity, the previous drawings showed the structure with the positive electrode coating 12 disposed on one side of the positive current collector 11 and the negative electrode coating 22 disposed on one side of the negative current collector 21. Please refer to [reference needed]. Figure 11 In practical applications, in order to achieve process objectives such as increasing the charge and discharge rate, this application may also provide a positive electrode coating 12 on the opposite two sides of the positive current collector 11 and a negative electrode coating 22 on the opposite two sides of the negative current collector 21.

[0051] According to one embodiment of this application, the number of positive grooves 121 corresponding to each positive electrode coating 12 is positively correlated with the charge and discharge rate of the electrode assembly, and the number of negative grooves 221 is positively correlated with the number of positive grooves 121.

[0052] During high-rate charging and discharging, the current flowing through the electrode assembly is greater, resulting in a higher current density for the same area. This makes the negative electrode more prone to increased polarization and localized overpotential, potentially inducing side reactions such as lithium plating. In this embodiment, the number of positive grooves 121 and negative grooves 221 are both positively correlated with the charging and discharging rate, ensuring the ability to consume lithium ions under high-rate charging and discharging conditions, thus guaranteeing battery safety and cycle life.

[0053] According to one embodiment of this application, the positive current collector 11, the negative current collector 21, the positive electrode coating 12, the negative electrode coating 22, and the separator 30 all extend in a first direction, the positive groove 121 penetrates the positive electrode coating 12 in a second direction, and the negative groove 221 penetrates the negative electrode coating 22 in a second direction; wherein, the second direction is parallel to the surfaces of the positive current collector 11 and the negative current collector 21 and perpendicular to the first direction.

[0054] The positive groove 121 and the negative groove 221 penetrate the positive electrode coating 12 and the negative electrode coating 22 respectively in the second direction, making the morphology of the active material more stable in the second direction and avoiding stress concentration and performance inhomogeneity caused by local thickness differences or collapse. At the same time, the grooves penetrating in the second direction facilitate the electrolyte to fully wet the interior of the electrode along the groove channels, allowing the electrolyte to enter the coating depth more smoothly, reducing the risk of gas stagnation and bubble formation in internal corners or narrow areas, thereby improving the effective reaction area of ​​the electrode and the uniformity of interface contact.

[0055] According to one embodiment of this application, each negative groove 221 has a dimension of 8-12 mm in the first direction, and the average depth of each negative groove 221 is 1 / 4-1 / 3 of the thickness of the negative electrode coating 22; and / or each positive groove 121 has a dimension of 5-10 mm in the first direction, and the average depth of each positive groove 121 is 1 / 4-1 / 3 of the thickness of the positive electrode coating 12.

[0056] If the size or depth of the positive groove 121 and the negative groove 221 (hereinafter collectively referred to as grooves for ease of description) is too small, the grooves will have limited effect on the conduction, wetting, and gas release of the electrolyte, making it difficult to introduce the electrolyte into the coating in a timely manner, and will not contribute enough to reducing polarization and increasing the effective reaction area. If the size or depth of the grooves is too large, it will significantly weaken the local coating support, easily introduce stress concentration, affect the mechanical strength of the electrode and the adhesion of the coating, and even cause problems such as coating cracking and powder shedding during the winding / stacking process. The parameter selection in this embodiment can ensure that the grooves can provide sufficient anti-lithium plating optimization on the one hand, and avoid excessively weakening the active material loading and structural strength on the other hand, thereby achieving a balance between electrochemical performance and structural reliability.

[0057] This application also provides a single-cell battery, including any of the above-mentioned electrode assembly and housing, wherein the electrode assembly is disposed within the housing.

[0058] This application also provides a method for processing an electrode assembly, including the following steps: A positive current collector 11 is provided, and a positive electrode coating 12 is applied to the surface of the positive current collector 11 at intervals; A negative current collector 21 is provided, and a negative electrode coating 22 is coated on the surface of the negative current collector 21; Positive grooves 121 are formed at both ends of each positive electrode coating 12, and negative grooves 221 are formed in the negative electrode coating 22; A diaphragm 30 is provided, and a positive current collector 11, a negative current collector 21 and a diaphragm 30 are stacked, such that the positive electrode coating 12 and the negative electrode coating 22 alternately sandwich the diaphragm 30, and the positive groove 121 is opposite to the negative groove 221.

[0059] It should be understood that after the positive electrode coating 12 and negative electrode coating 22 are coated on the surface of the positive current collector 11 / negative current collector 21, the positive electrode sheet 10 and negative electrode sheet 20 are actually formed. When the positive current collector 11 and negative current collector 21 are stacked, their surfaces carry the positive electrode coating 12 and negative electrode coating 22. In fact, the positive electrode sheet 10, negative electrode sheet 20 and separator 30 are stacked. The description of stacking the positive current collector 11 and negative current collector 21 is only from the process perspective. The transfer, clamping and feeding entities in this step are the positive current collector 11 and negative current collector 21.

[0060] Since the single cell provided in this application includes the electrode assembly of the above embodiments, and the electrode assembly processing method is used to process the electrode assembly of the above embodiments, the single cell and the electrode assembly processing method also have the beneficial effects of the above embodiments. That is, since the upper limit of lithium ion deposition of the positive electrode is reduced and the lithium ion consumption rate of the negative electrode is increased, lithium deposition is less likely to occur.

[0061] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0062] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0063] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0064] The above description is merely a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the design concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. An electrode assembly, characterized in that, It includes alternately stacked positive and negative electrode plates, and a separator sandwiched between the positive and negative electrode plates: The positive electrode sheet includes a positive current collector and a positive electrode coating. The positive electrode coating is spaced apart on the surface of the positive current collector, and positive grooves are formed at both ends of each segment of the positive electrode coating. The negative electrode sheet includes a negative current collector and a negative electrode coating disposed on the surface of the negative current collector, wherein the negative electrode coating has a negative groove in the region opposite to the positive groove.

2. The electrode assembly according to claim 1, characterized in that, In the extending direction of the positive current collector, the depth of the positive groove decreases as it approaches the end of the positive electrode coating; and / or Multiple positive grooves are formed on the same section of the positive electrode coating. Adjacent positive grooves are interconnected in the extension direction of the positive current collector. The positive grooves near the end of the positive electrode coating have a greater groove depth than the positive grooves away from the end.

3. The electrode assembly according to claim 1, characterized in that, There are multiple negative grooves, and adjacent negative grooves are spaced apart.

4. The electrode assembly according to claim 3, characterized in that, The groove wall of the negative groove is perpendicular to the surface of the negative current collector used to coat the negative electrode coating.

5. The electrode assembly according to claim 1, characterized in that, The positive electrode coating includes a positive subtractive material region and a positive uniform coating region. The positive subtractive material region is used to form the positive groove, and the positive uniform coating region is used to uniformly coat the positive electrode active material. The negative electrode coating includes a negative subtractive material region and a negative uniform coating region. The negative subtractive material region is used to form the negative groove. The negative uniform coating region uniformly coats the negative electrode active material. The average thickness of the positive uniform coating region is the same as the average thickness of the negative uniform coating region. The average thickness of the positive subtractive material region is less than the average thickness of the negative subtractive material region.

6. The electrode assembly according to claim 5, characterized in that, The negative material reduction area is also provided with a compensating ridge, which is sandwiched between two adjacent negative grooves.

7. The electrode assembly according to any one of claims 1-6, characterized in that, The number of positive grooves corresponding to each positive electrode coating is positively correlated with the charge / discharge rate of the electrode assembly, and the number of negative grooves is positively correlated with the number of positive grooves.

8. The electrode assembly according to any one of claims 1-6, characterized in that, The positive current collector, the negative current collector, the positive electrode coating, the negative electrode coating, and the separator all extend in a first direction. The positive groove penetrates the positive electrode coating in a second direction, and the negative groove penetrates the negative electrode coating in the second direction. The second direction is parallel to the surfaces of the positive current collector and the negative current collector and is perpendicular to the first direction.

9. The electrode assembly according to any one of claims 1-6, characterized in that, Each of the negative grooves has a dimension of 8-12 mm in the first direction, and the average depth of each negative groove is 1 / 4-1 / 3 of the thickness of the negative electrode coating; and / or Each of the positive grooves has a dimension of 5-10 mm in the first direction, and the average depth of each positive groove is 1 / 4-1 / 3 of the thickness of the positive electrode coating.

10. The electrode assembly according to any one of claims 1-6, characterized in that, The positive electrode coating is disposed on one side or opposite sides of the positive current collector; and / or The negative electrode coating is disposed on one side or opposite two sides of the negative current collector.

11. A single-cell battery, characterized in that, include: The electrode assembly as described in claims 1-10; The housing contains the electrode assembly.

12. A method for processing an electrode assembly, characterized in that, Includes the following steps: A positive current collector is provided, and a positive electrode coating is applied at intervals on the surface of the positive current collector; A negative current collector is provided, and a negative electrode coating is applied to the surface of the negative current collector; Positive grooves are formed at both ends of each positive electrode coating, and negative grooves are formed in the negative electrode coating; A diaphragm is provided, and the positive current collector, the negative current collector, and the diaphragm are stacked or wound such that the positive electrode coating and the negative electrode coating alternately sandwich the diaphragm, and the positive groove is opposite to the negative groove.

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